Boring bar



May 1511 I w; s. HUTCHENSON 2,553,94g

BORING BAR Filed April 11, 1949 1 9770M Pll/VE Z 1 0 1 2 19067204094! P141767 75 i020 0 7 T UIK 6 c1 DIR 0 IN V EN TOR.

William Hair/617M012 the bit to provide the clearances.

Patented May 8, 1951 UNITED STATES FATE-NT OFFICE 2 Claims.

The invention relates to a boring bar having a bit holder, and has for its object to provide such a holder to enable the time of the operator to be saved in connection with the grinding of the bit.

In this improvement the front and side rakes of the bit are pre-determined by a channel in the boring bar and it is only necessary to grind Inclinations of the channel to the longitudinal axis of the holder determine the most efiective rakes, both front and side. A full length of tool bit may be used, thus enabling the use of a standard tool bit. As the rakes are determined, by reason of the improvement, by the channel in the boring bar itself, the grinding of the front and side rakes is dispensed with. Depending on the different metals to be worked, the tool bit can be ground for clearance to any shape in respect to such already determined rakes without changing said rakes. Thus only clearance grinding is necessary, which any mechanic can do, a skilled or expert grinder not being required as is the case for the grinding of rakes. The boring bar itself is usually horizontal. The tool bit slants downwardly away from the work, and provides the front rake, and the side rake is inclined from left to right (looking at the work) and also drops the chips away from the cut.

The invention then consists of a boring bar 2? having a channel with a contour substantially that of the exterior contour of a standard bit, said channel having its longitudinal axis at two inclinations to the longitudinal axis of the holder,

with sidewalls oi the channel askew to the longitudinal axis of the holder, to provide the desired front and side rakes of the bit, without special grinding of the rakes, it being only required to grind the cutting end of the bit, to provide the necessary clearance of the bit to the work.

The invention will be more fully described hereinafter, embodiments thereof shown in the drawings, and the invention will be finally pointed out in the claims.

In the accompanying drawings,

Fig. 1 i a perspective view of the improved boring bar with the bit therein;

Fig. 2 is a vertical section taken on line 22 of Fig. l, the bit being omitted;

Fig. 3 is a horizontal section taken on line 33 of Fi 2;

Fig. 4 is a vertical section taken on line 4-4 of Fig. 2;

Fig. 5 is a diagram of Fig. 3; Fig. 6 is a diagram of Fig. 2;

and about 8 to 20 toa horiozntal plane 22.

Fig. 7 is a top view of the bit shown in Fig. 1;

Fig. 8 is a front view of thesame;

Fig. 9 is a top view of another form of the bit; and

'Fig. 10 is a front View of the same.

Similar character of reference indicate corresponding parts throughout the various views.

Referring to the drawings, the boring bar III has a plane front surface II adapted to be brought near the work. A channel I2 extends diagonally across the boring bar I0 having a cross-sectional area slightly larger than the crosssectional area of the bit I5 to enable the bit .to lee inserted therein and to be moved therein. The longitudinal axis of the channel is inclined in two directions to the axis of the holder I0, preferably about 15 to 20 to a vertical plane 20 (Fig. 5), The channel I2 has its flat sides I2a, I21), I20, and I2d (Fig. i angularly disposed both to the horizontal and perpendicular '(Fig. 4) The channel I2 in the boring bar is made square for standard tool bits and is slanted from front down toward the back as in Fig. 5, where the direction 2| of the bit is shown in respect to the vertical plane 2t, and tilted from left to right as in Fig. 6, where the direction of the bit 23 is shown in respect to the horizontal plane 22, thereby predetermim'ng both front rake and side rake of tool bit in the boring bar itself. The bit I5 is held in the channel I2 by Allen screws, three (I3) on the top for holding tool bit down, and one (I3a) at the side of the holder IQ, for sidewise holding. The bit [5 projects slightly out of the channel I2 beyond the face II to enable the work (not shown) to be bored or machined.

Various cutting shapes of bits may be used. Two forms are shown; one in Figs. 7 and 8, and one in Figs. 9 and 10. In Figs. 7 and 8, an angular edge It makes an acute angle with an angular edge Il and the edges I6 and I! are formed by angular plane surfaces extending from edge I6 to edge I8, and from edge I! to edge I9. The most forward point I50. is the cutting point. In Figs. 9 and 10, the bit I5 has a different cutting point 35. Edges 30, 3|, 32 and 33, form the forward cutting point 35. The edge 32 is set back, a also the edge 33. These examples are shown to illustrate the clearance grindings. It is noted that the top surfaces of these bits were not especially ground to form rakes.

Among the advantages of the improved boring bar are: made to use standard tool bits full length. Made to hold tool bit at any predetermined side rake and front rake. Made to hold tool bit in approximate center of tool post center. Made to be held in tool post on approximate straight line with cut. Made to eliminate almost all side torque thereby eliminating almost all chatter. Made to take heavier cuts without side spring thereby cutting truer to set. A heavy out can be taken and tool and carriage drawn back and in again, and it will not have a second cut as most conventional bars do. With front and side rake already on tool bit it is easier and quicker to grind Without weakening tool bit in so doing. The cutting surface of top of tool bit does not ever have to be ground. Only clearance and front shape need be ground. The boring bar permits more strength and rigidity for any given diameter hole to be bored. The boring bar can, of course, be made in different sizes accommodating all standard tool bits. The tool bit itself is held by Allen set screws both up and down and sideways. The preferred boring bar has its front end with corners rounded off as shown in the front end by shading in Fig. 1. The tapered portion extends from the plane front surface I I and terminates before the known holding portion of the boring bar. The cutting surface of the tool bit projects out of the front side H of the front end of boring bar 10. This boring bar and tool bit combination eliminates most of the skill needed to grind tool bits as required in all conventional boring bars.

The front end of the boring bar is tapered, with the taper extending from the front surface H to a part of the boring bar. The boring bar at its rear end is square or rectangular to be gripped in a standard tool post, as known.

Reference is made to a companion application filed subsequent to this application but on even date herewith, under Serial No. 86,760 on April 11, 1949.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

I claim:

1. In a boring bar having a shank with left and right sides in the direction of its longitudinal axis towards its front, and with a front face perpendicular to said axis, and having a channel with an internal contour of the transverse exterior contour of a standard tool bit with an axis, having an inclination in respect to a vertical plane from said front face towards the rear of the shank, the combination of said channel axis extending from the front upper left side to the lower right side of the shank, and the walls of said channel being inclined to the vertical and to the horizontal with the highest corner adjacent the left side of the shank and with the left corner of the channel contiguou to said left side of the shank, whereby a tool bit having a front and side rake inserted in said channel extends laterally out of the left side of the shank and the top surface of the protruding end of the tool bit acts to slide the chips both ways away from the cutting edge, no other grinding of the tool bit, other than for clearance, being necessary.

2. The structure of claim 1, in which the inclination of the channel axis to a horizontal plane is 8 to 20, and the inclination of said axis to a vertical plane is 15 to 20.

WM. S. HUTCHINSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 779,289 Langer et a1 Jan. 3, 1905 1,262,701 Riedy Apr. 16, 1918 FOREIGN PATENTS Number Country Date 117,469 Australia Sept. 3, 1943 

